Telephone-exchange system.



H. G. WEBSTER.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED 13120.4, 1905.

- Patented Aug. 10, 1909,.

" UNITE snares earns ornron.

HARRY G. WEBSTER, OF CHICAGO; III LTNOIS, NSSIGNOR TO MILO G. KELLOGG, OF CHICAGO,

. ILLINOIS.

ehnnrnonn-sxonanen SYSTEM.

Specification ofLe-tters Patent.

Patented Aug. 10, 1909.

Application filed December 4, 1905. Serial No. 290,162.

To all whom it may concern:

Be it known that I, HARRY G. Wn'nsrnn, a

citizen ofthe United States, and resident of Chicago, county of- Cook, and State of 1llinois, have invented new and useiullmprovements in Telephone-Exchange Systems, of which the following is a specification.

The present invention relates to central battery" telephone exchange systems and Inoreparticularly to the organization of circuits and apparatus by which the supervisionof the subscribers lines is obtained by the Operator. In systems of this type, the \various subscribers telephone lines, termimating in the central oi'lice, are adapted to be connected, by suitable link-circuits with whichthe supervisory signals. are associated. In operation, these signals are displayed as soon as the operator plugs into an idle line,

so and are eifaced when the subscriber removes ingthe termindl'. of the link-circuit, with the jack-comprising the terminals .of the telephone line, and, when so connected, the circuitunder the control ofthe subscriber is 4omade and broken at the latters switchhook. By the closing of the former circuit, the energization of the difi'cronti-ally-wound electromagnet is sufficient to cause the display of the supervisory signal; and by the 4-5 closing of the latter circuit, the action of the windin s being differential, the energization ofa sai electromagnet. is' decreased suificiently toefface the supervisory signal.

The,'characte1 of the invention, together wi thits object andscope, will be best under-j stgod uponreference to the following descrilption 'and claims, taken in connection W11 the accompanying drawing. Referr ng, to the sai drawing, which illustrates diagrammatically two telephone lines represent the two subscribers stations. each of which is connected to the central office 0 by a telephone line comprising the limbs 1 and 2. Since both stations A and B are similarly equipped, it will be sufiicient to refor to the equipment of station A. At this station, the call-bell 3, connected in series 4 with the condenser 4, is bridged across the limbs 12. The transmitter 5 and receiver 6 are connected in series in a parallel branch between the limbs 1 and 2, which may be made and broken by the switch-hook 7 in the usual manner. The substation equipment herein disclosed is merely illustrative and any desired type of substation apparatus may be employed. The limbs 1 and 2- of the telephone line are connected at the central oflic e to the distributing-board 9. Line conductors 10 and 11 extend said limbs to the contact-sleeves 12 and contact-springs 13 of multiple-jacks 14 located on the switchboard. The extension-comluctor 10 is nor- 8-0 mally broken, and the portion connected to limb 1 is normally grounded through thearmature 15 of the line-signal-eiiacing electromagnet which is here shown as a cut-oil magnet or relay 16. The other portion of the extension'conductor 10 is connected to ground through the winding of the cut-oil relay 16. A grounded branch17, extending through the winding of the line-relay 18 and the battery B is normally connected to the oxtcnsion-conductor 11, but may be broken throu h the agency of the armature 19 of the cut-0' relay 16. The relay 18, wheriencrgized, closes a grounded branch from thei'rco side of the battery B to ground through a call-signal lamp 20.

The linlccircuit in the present instance comprises two link-conductors or strands 2122, connected between. the tips and sleeves, respectively, of the plugs 2324, and including incircui't the usual condensers 2,526.. Associated with theseconductors are theilistening and ringing keys designated 2728 and' 29-30, respectively. The closing of the listening-key 2728 completes a branch between the two link-conductors 21 and 23 which includes the condenser 31, re-

'' through the secondary of the said induction coil 33. The closing of the ringing-hey 2930, in cluding the generator 236, completes a circuit between the portions of the link-conductors 2122 connected to the calling-plug 24, through a branch including the generator 36, battery B, and resistance 37, the pole of the generator adjacent to the battery being grounded at 38.

The supervisory signals associated with the linkcircuit comprise the diil 'erei'ltiallywound electromagnets 394(1, which control the supervisory lamp signals 41 and 42, respectively. Each of'these lamps is included in a circuit ext nding from the live pole of the battery B to ground through the armatures 13 and 44, respectively, of the relays 39-4it Both relays are wound substantially alike. The windings 45, which are included in. the grounded branches 46 and 46 respectively, extending from the link-conductor 21, have individually a relatively greater number of turns than the windings 47 which a re included in the branches 4S-4S extending from the live pole of the battery B to the other link conductor 22.

In the operation 01' the system, it the subscriber at substation A removes his receiver 6, a circuit is com leted irom the battery B, through the winding of call signal relay 18, the branch 17, the extension conductor 11, limb ol' tlmtelephono line, through switchhook 7, receiver 6 and transmitter 5 at the substation, through limb 1 ol' the telephone line, extension conductor 10 and armature of the cut-oil relay to ground. This circuit causes the encrgization ol' the call signal 20. The operator thereupon inserts the answering plug into a Jack 14. This act completes a circuit 01' dclinitc resistance local to the exchange and through the winding of cut'oll relay 16, as follows: l'rom the free pole ol' battery 13, through branch 48, including winding 47 01' the supervisory relay 31), liiik-comluctor 22 to the sleeve ol the plug); .L fifthcncc through the sleeve 12 01' the la cl; and the winding of the cut-oll' relay 16, to ground. to break the grounded branch 17 and to complete the circuits between the portions olthe extension conductor 10. The breaking ol' the: former branch removes the call signal 20 from the control of the subscriber at the substation A, while the completion of the circuit between the portions ol the. extension conductor ll) completes the metallic circuit from the substation to the operators set, which may be included in circuit by-closing the listenimg-liey 27--2S. it should be noted that when the operator inserts the plug 23 into one of the jacks 14, not only is a circuit completed through the nindhig; 17 of the supervisory relay 31), but also through the windinu lfi ol'said relay. lhccircuit through the latter windingmay be traced as follows:

This causes the cut-oll' relay from the free pole of the battery B through the branch 48 including the winding 47, linkcomluctor 22, sleeve of the plug 23, contact 12 01' the ack 14 to the winding of the cut-off relay 16 as bel'rn'e, thence through the armature 15, conductor 10, limb 1 ol' the telephone line, through the substation, limb 2 ol' the telephone line, extension conductor 1.1 to the contact spring 13 of the jack 14, thence through the tip 01' the plug 23, link-conductor 21 and grounded branch 46 which includes the winding 45. The windings 4.5 and 47 are opposed and so n'oportioned that when both of these circuits are completed, the armature 43 will not llO'HlFtlWn against its contact to complete the circuit through the supervisory lamp 41. When the operator has closed the listening-key 27-2$ and obtained the wishes of thecalling subscriber at station A, assuming' that the desired station is station 13, she will then test the circuit of the latter station by touching the tip 01' the plug 24 against a sleeve 12 of one 01' thejacks 14 01' the latter line.

From the circuits previously traced, it will be seen that if the latter line is busy, there will be a potential on the sleeve 12 which will cause a ilow of current .lroln the said sleeve 12, through the tip of the. plug 24, the

link-comluctor 21 and the brai-ich 46 including the winding of the supervisory relay 4(),to ground. ith the listening-key 2728 closed at this instant, the operator will obtain a click in her receiver 32, indicating the busy condition of the line. If the line is found to be idle, the operator will insert the plug 24 into a jack 14 of the telephone line running to the substation B. This act will complete a circuit local to the exchangenml through the winding: 47 of the supervisory re-. lav 40, as follows: from the tree pole ol the battery 13, through the branch 48' windiln i I h 47 of relay 41), linli-eomluclor 22, sleeve of the plu'-"24-, sleeve 12 of a jack 1% and extension conductor 11) through the winding oi rclay 16 to ground. 'lhis will cause the energization ol' the cut-o'll' relay and disc mnect the call signal 20 from the line, thus removing it beyond the coul rol ol' the subscriber at Station B. The operator then closes 'the ringing-key 2)-3U and thereby completes a circuit from the generator, through the contact 29 of the ringing-key, link-comluctor 21, tip of the plug 24 spring, contact 13 of the jack 14, extension conductor 11, limb 2 of the telephone line, the condenser and call-bell at station 13, limb 1 ol the telephone line, extension conductor 10 including the armature 15 of the cut-o'li' relay 16, sleeve 12 'ol' the jack, sleeve 01 the plug 24', link-conductor 22, the contact 3001' the ringing-key, resistance 37, battery B to the generator. The closing of this circuit actuates the call-bell at the substation B to call the subscriber at said station. The closing of this circuit also breaks the circuit from the battery B through the winding of the cut-oil relay 16. Therefore, in orderto hold the cut-off relay in the proper position. to maintain the ringing circuit to the substation, the battery B is preferably employed to supply current. to the windlng of said cut-off relay. The circuit through this winding may be traced from the ground at 38, through the battery B", resistance 37, contact of the ringing-key, link-conductor 22, sleeve of the plug 24, sleeve 12 of the jack 1.4 and a portion of the extension conductor 10, through the winding of the relay 16 to ground. The resistance 37 is included in this circuit merely for the purpose of protecting the system from an excessive flow of current in case of a ground on the telephone line. For example, in case of a ground on the limb 1 running to station E, without the resistance 37 thebattery B? would be short circuited and an injurious flow of current would result.

By the insertion of the plug 24 into a jack 14, a second circuit, 0 on only at the substation 13, is formed. T is circuit includes the Winding 45 and, as previously traced, ex-

tends from the free pole of the battery'B through the winding 47 of the relay 40, thence through the cord-conductor 22 and the extension conductor. 10, limb 1 of the telephone line extendin to the substation B I through the branch inc uding the transmit;

ter, receiver and switch-hook at said substation', through the limb 2, extension conductor 11, linkconductor 21- and dgrounded branch 46', through the other win mg 45 of the supervisory relay 10. It will be noted that this circuit is completed at all points except the subscribers hook-switch, and that the energization of the windin -47-'is sufficient to cause the display of t e signal 42. This signal remains displayed until the subscriber at substation B removes his receiver andv thereby closes the circuit including both windings of the relay 40. This causes a decreased energization of the rela 40 and a conse uent efl'acing of the associated signal 42. it should be noted that the supervisory relay is marginal to this extent that practical] y the full energizing effect of the low effi-' ciency winding when placed in the local circuit of fixed resistance, that including the cut-off relay 16, is required to attract the relays armature while any material decrease from that energization will allow the armature to be retracted. When the subscribers have finished their conversation and hung u their receivers, the circuits controlling botli windings of both supervisory relays 39 and 40 will be broken, while the circuits local to the exchange, including windings 47 of said relays, will remain closed, thereby again causing a d splay of the signals 41 and 42 and thus indicating to the operator that coni vcrsation has been completed.

In carrying out my invention, in a twentyfour volt system, cut-off relays having five hundred ohms resistance each, and super visory relays having the windings 45 arranged to give three thousand five hundred turns and one hundred ohms resistance, and the windings 47 two thousand turns and one hundred ohms resistance, willbe found satisfactory. This is merely given as a typical example of the relative dimensions of these relays, which, obviously, may be varied to suit the exigencies of any given case. The different batteries, B, B and B, may obviously be one and the same battery, and the grounds associated therewith and with other parts of the system may be replaced by a connecting conductor. It will also be apparent that other alterations and modifications may be made in the specific matter disclosed, without departing from the spirit and scope of m invention; 1, therefore, do not wish to be limited to the precise arrangement illus trated and described, but aim to cover, by the terms of the appended claims, all such alterations and modlfications.

' What I claim as new and desire to secure by Letters Patent of the United States is:-

1. The combination'with a telephone line, of a cord circuit adapted for connection therewith, a supervisory signal for said circuit, a relay for controlling said signal, a winding of relatively low efliciency for said relay, a second winding of relatively high efficiency therefor, means for operatively including said first-mentioned winding in a circuit of fixed resistance on connection made with said line to operate said relay to display said signal, a substation switch for said line adapted when shifted to include said Winding in a circuit of less resistance and simultanegizing capacity operatively in circuit, said two windlngs being-then electromagnetically opposed to produce a decreased energization' 0 said relay to efface said signal.

2. The combination with a telephone line, ofa differential relay in circuit therewith, having two windings of different efficiencies, a switch at the substation of said line for for said line, and a path for current includin the winding of less efficiency and said cut'oiT relay to cause a preponderating current flow in said last-mentioned winding. 3. The combination with a telephone line, of a s )ringjack therefor at the exchange, a cut-o relay for said line-connected between a contact of said springjack and a local rea cord circuit having a terminal connected said cord circuit having differential windtings, one havlng a greater number of turns than the other, a path for current including 0usly include said winding of greater enercausing equal current flows through said substation through said windings, a cut-off relay turn conductor, a central source of current, i

with said springjack, a supervisory relay for said source, said windings, said terminal, said i In Witness whereof, I hereunto subscribe springjaek and 'seitl telephone line, and a, l my name this 2nd day of December, A. D branch path for current including the Wind- 1905.

ing of less efficiency, said cut-ofi' relay and HARRY G. WEBSTER.

return conductor to counter-balance the Witnesses:

greater efficiency of said other winding, sub- CAROLYN WEBER, stsrntnrlly as described. A. H. DYs0N 

